Viscosity reduction is an important quality index of gelatin, and hard capsule manufacturers have strict requirements for this. Some customers require less than or equal to 7%, while others require less than or equal to 5%. In the light industry standard QB2354-2005, it is clearly stipulated that when the 6.67% glue concentration is kept at 37 ℃ for 24 hours, the viscosity decline should be less than or equal to 10%. Bacterial contamination in the production process is not the only reason for the decline in high viscosity, but it is also the main reason.
Therefore, the viscosity decline value can be measured in a short time, the detection time can be shortened, and the viscosity decline range can be mastered, which has a certain guiding effect on the production and preparation of gelatin. For this reason, the viscosity drop values at 37 ℃ and 60 ℃ were tested and compared, the viscosity drop values at different times were measured, and the influence of temperature on viscosity was analyzed.
1 Experimental part
1.1 Experimental Instruments
(1) Bosch viscometer (ND-1);
(2) incubator (temperature can be controlled at 371 ℃);
(3) Electric thermostatic water bath (adjustable to 65.1 ℃);
(4) Stopwatch.
1.2 Testing Solutions
Weigh a certain amount of commercial dry glue and prepare 6.67% glue into 300 ml. The viscosity and viscosity decline were measured.
1.3 Experimental methods
(1) Comparison of viscosity decline at different temperatures.
(2) Sample collection: 21 samples were randomly obtained over a period of time.
(3) The collected samples were prepared into 6.67% glue according to the viscosity measurement method QB2354-2005. After the viscosity was measured, the sample was incubated in an incubator at 37 °c for 24 hours and in an incubator at 60 °c for 18 hours. The viscosity is then measured and the drop is calculated.
1.4 Results and discussion
After incubation at 37 ℃ for 24 hours and at 60 ℃ for 18 hours, the viscosity of 21 samples decreased.
In order to study the relationship between viscosity reduction and culture time, 6.67% glue was used for culture at 37 ℃ according to QB2354-2005 viscosity measurement method. Measured after 3 hours and every 3 hours.
According to the contrast value and viscosity reduction results, after incubation at two different temperatures, colloidal solutions with the same concentration (6.67%) have different viscosity reduction values, which may be related to the entropy, enthalpy and microorganisms of the colloidal solution.
From the analysis of the results, the viscosity decrease value measured at 60 ℃ for 18 hours is less than 20%, and the viscosity decrease value measured at 30 ℃ for 24 hours is less than 10%. If the semi-finished gelatin is cultured at 60 ° C for 18 hours, the viscosity reduction value is determined, which can be shortened by 6 hours in practice. This not only guides the production needs, but also meets the requirements of gelatin blending.
The decrease of viscosity increases with time. And the rate of increase is slower. However, more experiments are needed to determine whether the decrease in viscosity will vary more over time.